The conflict was the deadliest in human history with estimated deaths ranging from 50 million to over 70 million soldiers and civilians.[1] It ended with the Soviet Union dominant in a part of Central Europe and all of Eastern Europe, and the U.S. and its allies dominant in Western Europe, a part of Central Europe and Scandinavia, setting the stage for the Cold War.

War Begins in Europe

In the immediate run up to WWII, there were frequent reports of trespassing Polish troops. On August 31, 1939 German covert operatives staged a fake attack by Polish troops on a German radio station. WWII started on September 1, 1939, when German troops invaded Poland. Hitler justified this as a defensive act, pointing to the frequent border incidents, and said famously that from this moment on Germany would strike back.

The major tactical innovation of the war was the use of combined arms warfare, typified by the German doctrine of blitzkrieg. In this style of warfare armor, infantry, artillery and air power (see Luftwaffe) all coordinate to achieve overwhelming superiority at point on the enemy lines. Armor and fast-moving infantry units then exploit the gap and penetrate deep behind enemy lines. The objective is to cause a widespread collapse of the enemy's ability to fight. It was particularly effective during the early stages of the war, before the Allies developed effective countermeasures.
On September 17, 1939, Poland was invaded from the east by Hitler’s ally, Stalin.

War in the West

A Canadian soldier in the ruins of Caen, 9 July 1944

Once the invasion of Poland was complete, German forces regrouped while French and British forces remained on the defensive, leading US commentators to dub it the Phoney War. May 10 1940 made clear that the war was real, as Germany invaded France, occupying neutral countries such as the Netherlands, Luxembourg and Belgium in the process. Resistance by the British and French armies proved ineffective, and France was soon surrendered. British and French troops were routed and evacuated mainland Europe at Dunkirk. France was divided into the northern Occupied France and the collaborationist Vichy regime in the south of France, including Corsica.

The collapse and occupation of France, together with Germany's non-aggression pact with the Soviet Union,[2], Germany's alliance with fascist Italy and an expansionist Japan, the benevolent neutrality of fascist Spain, and the fact that little of Europe was outside Axis control, led many to assume that Britain had been defeated. Indeed it would appear that the seemingly foolish decision of the relatively weak Britain to continue the war took the Axis powers off guard. This decision ensured the remaining British Empire was still involved in the war, with Japan threatening many British possessions in Asia.

In 1940 Denmark and Norway were invaded by German forces, to preempt a British occupation of Norway and occupy its coastline and ports to be used by the Kriegsmarine. Norway also contained a source of Heavy water, potentially crucial in the construction of an atomic weapon. The operation was successful, but losses were heavy, especially to the Kriegsmarine. This was soon followed by the British troops invited by Iceland and American occupation of Greenland. (The goal was to prevent any increase in the range of German air and submarine activity, brought about the occupation of these lands - and of the Azores at the request of the Portuguese Government.)

With Britain the sole opposing European nation, the Battle of Britain commenced. The Luftwaffe attempted to achieve aerial dominance over the south of Britain, in order to allow a sea based invasion of the British Isles to proceed. From 10th July to the end of October the Royal Air Force and the Luftwaffe fought for dominance; the resilience of the RAF, which counted in its ranks also Commonwealth personnel, US volunteers and Polish and Czech exiles, and the use of radar and its associated early warning systems, had forced a rethink of German tactics. It was the first significant setback for the Germans in the War. They now concentrated on the great population centers, especially London, hoping that huge civilian casualties would weaken morale and lead to a lessening of the war effort by the populace. The period that followed, popularly known as the Blitz, lasted into May 1941. Around 40,000 civilians and civil defense workers died; but the Germans failed to reach their objectives and their resources were soon diverted to the Eastern front as Hitler began concentrating on the impending invasion of the Soviet Union.

With the pressure off their airbases the RAF was now able to increase its nightly raids on industrial sites in Germany and occupied lands. Because of the inability to correctly target these sites, the raids soon turned into “area bombing”, and German civilian casualties rose. These raids were to reach further into Germany as the war progressed and were greatly increased when American bombers began their sorties.

Finnish Wars

The Soviet Union invaded Finland, a neutral, on November 30 1939. This conflict came to be known as the "Winter War". Despite the overwhelming numbers of the Red Army, the Finnish resistance was strong and the battle was hard fought before the Soviet army took control. Outside powers (including the U.S.) considered intervention to help Finland; only a little aid trickled in and Finland was forced to sue for peace. The peace treaty signed in March 1940 favored the Soviets, but they paid heavily for their victory with 200,000 dead. Finland lost 25,000 dead, and had to absorb 400,000 refugees from areas turned over to the Soviets. In 1941 Finland joined Germany in attacking the Soviets, in the "Continuation War" (1941-44), but lost again. An armistice in Sept. 1944 stabilized the border, using March 1940 lines; in addition Finland had to pay heavy reparations and had to remain neutral in the Cold War.[3]

Soviet-German War

1941 marked the major turning point in the war in Europe, when the Germans undertook Operation Barbarossa - the invasion of the Soviet Union. Stalin was repeatedly informed by his own spies and anti-German countries that Germany was about to attack; he rejected the accurate reports and paid dearly for the blunder.

In June--behind schedule because of diversions in the Balkans--the Germans launched their massive war against the Soviet Union (known as the "Great Patriotic War" in Russia). It was by far the largest, bloodiest, and most decisive phase of World War II. Outside observers in the first few months figured that Germany would win easily. But the Nazi armies were split three ways, logistics became worse and worse as distances grew, and none met their objective by the time the extreme Russian winter of 1941-42 set in. Blitzkrieg had failed against the Soviets, and the Germans lacked the resources to fight a long war against a country with such vast areas and so many more people. The Luftwaffe, which promised to overcome the slowness of ground travel, failed to provide adequate support and was soon matched and outnumbered by the Soviet air force.[4]

In the third year of war Germany began to suffer from a lack of important resources such as oil. Hitler therefore ordered the German army to take the city of Stalingrad and the oil fields of Baku in South Russia. The operation failed after the 6th German army was encircled in Stalingrad and completely annihilated. The Battle of Stalingrad marked a turning point in the war and the Soviet Union started launching their own offensives. After a time of comparatively slow progress, the brilliant Soviet officer, Konstantin Rokossovsky, engineered "Operation Bagration", named-so after the Napoleonic Russian hero. The operation was extremely successful for the Soviets, leading to around 600,000 Soviet casualties and over 500,000 German casualties, including over 60,000 German vehicles and tanks. Even the Germans' best officer, Erich von Manstein, couldn't turn the situation around. Finally, in 1945, Soviet troops stormed Berlin, and forced Nazi Germany into capitulation.

Far East

After Pearl Harbor, the Japanese juggernaut seemed unstoppable. In the south, they conquered the Philippines, the oil-rich Dutch East Indies, Malaysia, and extended their reach as far as the Solomon Islands. In the west, they seized Burma and the vital port at Rangoon, and even attacked British forces at Ceylon. The Japanese empire now reached as far as Wake Island in the east and the Aleutian Islands to the north. Attacks on Japanese targets, including the Doolittle raid, boasted American morale, but did little material damage. In May 1942, Japanese forces were finally halted at the Battle of the Coral Sea, which cost the Americans a precious aircraft carrier, but saved southern New Guinea. At the Battle of Midway a month later, the Japanese lost four of their best carriers, suffering a blow to their sea power from which they never recovered.

The Americans took the offensive in August with a landing on the island of Guadalcanal. The overall American offensive strategy was two-pronged. Forces in the south advanced up the Solomon island chain and New Guinea, while in the central Pacific, Marines took island after island, including Tarawa, Eniwetok, Saipan, and Guam. The two lines of attack came together at the Philippines.

Integral to the strategy was the policy of island hopping. Many Japanese strongholds were bypassed, allowing the American forces to concentrate on more strategically significant islands. For example, Truk and Rabaul were home to major Japanese air and naval bases, but once the bases were neutralized, there was no reason to take on the troops there. This policy not only saved thousands of American (and Japanese) lives, it shortened the war by at least several months.

The American invasion of the Philippines took place in late October of 1944 when Marines landed on Leyte Island. A few days later, the US Navy shattered what was left of Japanese naval power in the Battle of Leyte Gulf. The Japanese fought hard, however, and Leyte took two months to secure. When the Americans landed on the other islands, they found the troops there equally unwilling to retreat, but with American superiority in almost every area, the outcome was never really in doubt. Manila was captured by March, and the American position had become solid enough that leaders could start preparing for the final stage: the invasion of Japan. The first step was taken when the island of Okinawa was captured in June after two months of heavy fighting. Operation Olympic, the invasion of Kyushu, was scheduled for November 1945, followed by Operation Coronet, the invasion of Honshu, in March of 1946.

The Japanese, soldiers and civilians alike, were expected to put up a fierce defense. Army Chief of Staff George C. Marshall believed that Japan would fight to the last man, and insisted on preparing for a land invasion of Japan with an army of 2,000,000 men anticipating a tremendous number of casualties. Some analysts estimated the number of projected casualties from Operation Olympic alone at 250,000 dead and wounded.[5] For this reason, Washington strongly requested the Soviets declare war on Japan. At the Potsdam conference in mid-July 1945, Stalin told President Truman the Soviets would declare war on Japan but would not give a firm timetable.[6] (This was the last of the four "Allied" conferences, taking place in mid-July 1945; the other three were: the Tehran Conference from November 28 to December 1, 1943; the Cairo Conference from November 22 to November 26, 1943; the Yalta Conference from February 4 to February 11, 1945.)

Time Line of Pacific War

Japanese capitulation

After the successful atom bomb test in the U.S., President Truman was left with the immense task of deciding what to do with the power of the atomic bomb. Truman assembled a committee to advise him. The committee recommended the bomb should be used on the Japanese Empire mainland to save American lives and produce maximum shock to try to convince the Japanese to surrender.[7] Therefore, on August 6, 1945, a B-29 Superfortress, the "Enola Gay" piloted by Paul Tibbet, dropped an atomic bomb (now called a nuclear weapon) on Hiroshima. Japan did not respond, so on August 9, "Bocks Car", a B-29 piloted by Frederick C. Bock dropped the second atomic bomb on Nagasaki.[8]

The Soviet Union declared war on Japan at midnight August 8, 1945, in response to the American requests and in a last-minute grab for the spoils of war. It invaded Manchuria and Korea with 1.6 million troops; the Japanese army disintegrated. The Soviets captured 600,000 military and civilian prisoners of war; most of whom never returned home again.[9] It was no longer possible for the Imperial Army to defend the emperor. On August 15, 1945, Emperor Hirohito by radio broadcast announced Japan would accept the terms of the Allies, unconditional surrender.[10] By follow up message, the Japanese government stated they were surrendering with the understanding the Emperor would remain on the throne and would not be hung as a war criminal. Washington agreed, saying the authority of the emperor would be "subject to the Supreme Commander of the Allied Powers." On September 2, 1945, the Japanese Emperor formally surrendered all Japanese forces to the Allies in a famous ceremony aboard the battleship USS Missouri in Tokyo Bay. This was the ending of World War II, after six years almost to the day.

Effects of war on empires

The Red army conquered practically everything east of the "Iron Curtain," destroying independent national governments and making them all subservient to Moscow. The US grudgingly tolerated this imperialism until 1947, when it was Greece's turn. Then the US drew the line and adopted a policy of containment. Because of the geography of war, Yugoslavia and Albania escaped the Red Army. They fell under the control of independent Communists--Yugoslavia received American support, and Albania turned to Red China for help against the Soviets.